The present invention relates generally to an apparatus and method of external skeletal support. More particularly, the invention relates to such an apparatus and method of external skeletal support (e.g., through in-vivo fixation) having a component for angular rotation (e.g., knee flexion and extension) and a skeletal support component for relative lateral rotation (e.g., tibial external-internal rotation). Several embodiments of the apparatus and method are particularly adapted for skeletal fixation of skeletal elements and/or for bridging a knee joint or similar joint or ligaments, and in the treatment of tibial fractures and flexure contractures.
The repair of traumatized bone or ligaments is sometimes accomplished through the use of an external skeletal fixation apparatus which includes a number of curved rings or curved semi- or half-rings (referred to collectively herein as xe2x80x9cringsxe2x80x9d or xe2x80x9cring elementsxe2x80x9d). The rings are positioned generally about the bone or ligaments (hereinafter xe2x80x9cskeletal elementsxe2x80x9d) and spaced apart (i.e., along the longitudinal axis of the bones(s) being treated or supported), but structurally connected via, for example, a plurality of tie rods. In this way, several rings and several tie rods may be used by the surgeon to create an overall frame about the patient""s arm, leg or ankle. Further, pins or wires may be fixed to the rings and extend transversely therefrom into the bones, so that the frame and pins support and/or load the bone tissue in a desired manner. Such a system and method has been referred to in the art as the xe2x80x9cIlizarov Technique.xe2x80x9d The Ilizarov Technique is described generally in U.S. Pat. No. 4,615,338, issue to Gavril A. Ilizarov et al., hereby incorporated by reference. An improvement to the Ilizarov Technique is described generally in U.S. Pat. No. 5,074,866, issued to Sherman et al., on Dec. 24, 1991, also hereby incorporated by reference.
One application to which the present invention is particularly adapted is the treatment of knee and ligament damage, tibial fractures and flexure contractures. External skeletal fixation for these purposes allow for the flexion or extension of the knee (i.e, angular rotation of the tibia relative to the femur) but do not typically allow for lateral rotation of the tibia (i.e., internal-external rotation relative to the knee or femur). Prior art skeletal support methods which provide for internal-external rotation of the tibia relative to the femur have done so through the use of bracing and other ex-vivo skeletal support elements. Although these support elements often provide adequate support for the damaged skeletal element, these do not positively fixate the skeletal element, as would the use of certain in-vivo connector elements such as pins. As an example, U.S. Pat. No. 4,751,920 discloses a pivoting knee brace with rotating and translating tibia collars. The brace is secured to the tibia and femur via straps, with collars positioned around the upper leg and the lower leg and connected via a connecting rod. A series of cams is also provided to control the internal-external rotation of the tibia relative to the femur.
Another skeletal support apparatus referred to as an orthotic device is disclosed generally in U.S. Pat. No. 5,121,742 (xe2x80x9clower extremity orthotic devicexe2x80x9d). The orthotic device allows the patient to have pivotal knee rotation by employing straps around the thigh and around the calf, and knee joints interspaced between the thigh and calf side numbers. The knee joints are interconnected with the straps by a cable system which allow the knee to be placed in the locked or unlocked position, by utilizing a cable system interconnecting the components of the device.
It is one of multiple objects of the present invention to provide an external skeletal support apparatus or fixation apparatus that allows for lateral or external-internal rotation of one skeletal element(e.g., the tibia) relative to an interconnected second skeletal element (e.g., femur). It is a further object of the invention to provide such an external skeletal apparatus or fixation apparatus to bridge a joint between two skeletal elements allowing for and supporting angular rotation about the joint (e.g., knee flexion and extension) and lateral rotation of one skeletal element relative to the joint or other skeletal element (e.g., internal-external rotation of the tibia).
Generally, an external skeletal support apparatus according to the invention supports relative movement between at least two skeletal elements (e.g., a femur and tibia). The apparatus includes a first external support section for rigidly supporting a first skeletal element, a second external support section for rigidly supporting a second skeletal element, and a hinged support section interconnecting the first and second external support sections such that the hinged support section pivots to support and/or control the joint through angular rotation (e.g., knee flexion or extension) and/or relative rotation between the two skeletal elements. The second external support section includes at least a first support element and a second support element, which are rotatably coupled such that the second support element is positioned to rigidly support the second skeletal element and is rotatable relative to the first support element with generally lateral rotation of the second skeletal element (e.g., external-internal rotation of the tibia).
In one application, an external skeletal fixation apparatus is provided to support a joint such as the knee joint. The apparatus includes a first external support section rigidly supporting a skeletal element on one side of the joint and a second external support section rigidly supporting a skeletal element on an opposite side of the joint. Further, a hinged support section interconnects the first and second external support sections in the vicinity of the joint such that the hinge support section pivots the joint about a generally lateral axis when the joint is rotated through flexion or extension. The second external support section includes at least a first support ring element and a second support ring element rotatably coupled with the first support ring element. The first support ring element is rigidly connected with the hinged support section and the second support ring element rigidly supports the second skeletal element such that the second support ring element is rotatable relative to the first support element with generally lateral rotation of the second skeletal element relative to the first skeletal element or the joint. Connector pins are preferably used in the support sections to fixedly attach ring element in-vivo with the skeletal element.
Moreover, at least one coupler is preferably used to dynamically couple the second support ring element with the first support ring element such that the second support ring element is rotatable relative to the first support ring element along a predetermined arc path. In one embodiment, the coupler includes a base component having a guide rail and fixedly attached to one of the first and second support ring elements. A slider component is also provided for fixedly attaching to the other support ring element and for slidably engaging the guide rail. The slider component may include a slider block attachable with one support ring element and a slider insert having a first portion lockingly connected with said slider block and a second portion slidably engageable with the rail. Alternatively, the slider block and insert may be formed integrally as a one-piece metallic component.
Compared with known skeletal fixation devices, the inventive fixation apparatus provides for a fixation method that more effectively, and to a greater extent, restores natural mobility. The apparatus is more convenient and comfortable to use and enhances the healing process. Alternatively, compared with known ex-vivo types of skeletal support devices, the skeletal support apparatus according to the invention also provides better support and comfort, and thus, is more effective in enhancing the healing process.
These and other objects, features, and advantages of the present invention will become apparent to those skilled in the art from the following detailed description of one or more preferred embodiments and the accompanying drawings.